Background

Authors of this study used expanded prostate cancer index (EPIC) to study factors that could predict for bowel toxicity in this patient group.

Methods

Patient treated with definitive radiation were prospectively enrolled between 2003-06.

Telephone interviews were used to collect quality of life baseline and patient reported outcomes (PROs) at various time points up to 2 years.

Bowel quality of life scores were assigned to patients at different time intervals based on patient responses to questions regarding urgency, frequency etc.

Various DVH constraints were used to assess relationship of dose and quality of life scores.

Results

Majority of patients, about 80%, had low or intermediate risk prostate cancer. 31% of patients also got androgen deprivation therapy.

All patients were treated to doses between 75-79 Gy.

There was a 16 point decline in bowel quality of life at 2 months, however at 6 months scores were back to baseline.

At 24 months there was a slight decline from baseline: 14% of patients had urgency, 8% with frequency and 11% with overall bowel problems.

On multivariate analysis, baseline score was significant predictor of worse bowel quality of life.

Aspirin use and V70>25% were significantly related to decrease in bowel quality of life especially in regards to bleeding and urgency.

83% of patients received IMRT. There was greater decrease in bowel quality of life in patients who didn't get IMRT, but this difference disappeared at 6 months.

In regards to the rectal constraint, 86% of patient with IMRT had acceptable V70 rectal constraint vs 71% of patients with non-IMRT treatment.

Conclusions

At 2 years a minority of patients have severe bowel problems.

Quality of life differences in IMRT vs non-IMRT treatment disappears at 6 months.

Rectal dose of V70<25% and aspirin use were significantly related to poor bowel quality of life.

V70<25% constraints for rectal dose in treatment of prostate cancer should be maintained.

Clinical and Scientific Implications

This is an interesting study looking at patient reported outcomes for bowel toxicity after radiation therapy. Future studies will be required to increase utilization of patient outcome measures. This study shows from a patient perspective, radiation is tolerated well in regards to bowel toxicity. Although there is a big push to expand IMRT treatment, there are not significant differences in patient reported outcomes for bowel toxicity when compared to non-IMRT treatment.